Patent GB-468415-A (GB)
Title: Improvements in automatic gear-changing devices for rail motor vehicles
IPC: F16H61/02
Filed: 1936-01-02
Abstract: 468,415. Controlling change speed gearing. BOURLET, A. Jan. 2, 1936, No. 183. [Class 80 (ii)] Change - speed gearing upon vehicles is changed by a compound centrifugal governor shown in Fig. 1, which is driven proportionally to the vehicle speed and imparts stepped displacement to a speed-changing shaft 68. Governor weights 65, 65<1> act to thrust right a sleeve 71 against the action of springs 73, 731, 71<11> and 73<111> in series which can expand and contract definite stepped distances formed by abut. ment discs such as 72<11> striking stops such as 75<11> and striking one another. The strengths of these springs are chosen in relation to the governor weights so that there is no stable intermediate position as a spring is being compressed, and compression goes on until the corresponding disc 72<11> strikes the next disc 72<111>, so that the sleeve 71 and shaft 68 move in steps both ways. The governor weights, of which there may be several, are pivoted at different distances from the vehicledriven governor spindle 62. The shaft 68 may control the gear box directly. An arrangement is described in which the shaft 68 displaces a drum 96, Fig. 3, with three sets of electric contacts upon it which are turned under three switch arms (not shown) connected to three coils 99, 991, 99<11>, Fig. 4. The coils can be excited in eight combinations corresponding to the eight combinations of terminals shown in Fig. 3. The coil 99 when excited opens a valve 103 to admit pressure air from a pipe 105 into a chamber 107 to thrust a piston 108 right a distance a. When the coil 99<1> is excited alone, a piston 1081 is thrust right a distance 2a. When the coils 99, 99<1> are both excited, the piston 1081 is moved a distance 3a. It is thus possible to impart eight different displacements to a rack bar 112 which turns a pinion 114 and gear-changing shaft 116. Means are described for delaying the actual gear change until the engine has slowed down. Between the pinion 114, Fig. 4, and the shaft 116, is a spring 147, Fig. 6 (not shown) which is stressed as the rack bar 112 moves, the gear-changing shaft 116 being held against turning by a pawl which is not tripped until a lever 154, Fig. 5, is raised. As the rack bar 112 is moved right by the servo mechanism, a pawl 120 engages and causes a switch lever 124 to rock anticlockwise so as to bridge wires 142 instead of wires 143. As long as the wires 142 are bridged, the engine keeps slowing down. The heel 126 of the switch lever 124 is engaged and locked in the raised position by a pawl 127, while the heel itself strikes and holds open a valve 136 admitting a rightward flow of air from a pressure pipe 140. This air fills a chamber 134 and then raises a piston 132 which raises the lever 154. This lever 154 trips the pawl 127 allowing the switch lever 124 to. fall and restore the normal working of the engine by bridging the wires 143. The lever 154 also trips the pawl holding back the gear-changing shaft 116 which is thus freed to effect the change which has been delayed after the engine began to slow down by the time taken for the chamber 134 to fill with air, a time which is adjustable by a screw valve 139.